Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Announcements and Chat > General Discussion

Reply
 
Thread Tools Search this Thread Display Modes
Old 14th April 2017, 02:55   #41  |  Link
Groucho2004
 
Groucho2004's Avatar
 
Join Date: Mar 2006
Posts: 3,878
Quote:
Originally Posted by manolito View Post
@Groucho

Didn't most of us start here writing about things of which we had insufficient knowledge?
I don't know how to write or talk about something of which I have little or no knowledge, nor would I want to. I know that there are people who have that skill, they usually have jobs in politics or marketing.
I prefer to do my research first. Thanks to the internet, this is a lot easier than 30 years ago when I had to go to the library on a regular basis.

Lastly, there is a difference between occasionally getting something wrong and writing stuff that consistently contains 70% nonsense and 30% padding.

Last edited by Groucho2004; 14th April 2017 at 23:23.
Groucho2004 is offline   Reply With Quote
Old 14th April 2017, 04:58   #42  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Is there a type of Xvid I've so far not discovered, because I'm a little confused about the claims that Xvid is as good or better than x264. Well.... I guess it can be, but the default h263 matrix throws away plenty of fine detail, (for "old hardware" compatibility you possibly need to use it), and if memory serves me correctly Xvid's B-Frames are somewhat average quality. It's also more prone to "blockiness" in flat areas, no matter how much bitrate you give it..... at least in my experience.

And Xvid has no quality based single pass encoding method as x264 does, so it's either pick a bitrate and hope for the best, which is far from ideal (remember when every AVI was 350MB or 700MB etc?) or run a compression test before encoding.

Mind you the mpeg matrix is better than h263, and some of the custom matrices (from memory) do a good job of retaining detail, but that's generally reflected in the bitrate. Not that I think anyone has mentioned the matrix they use with Xvid, although a custom matrix could hurt hardware compatibility.

Is there a name for the "hazy" compression artefacts around subtitles or sharpish edges that I recall were inevitable for Xvid but far less of a problem for x264?

I ran a few little sample encodes just to see. It's a 1080p source downscaled to 960x396 (Spline36) for encoding, then upscaled to 1080p again on playback by MPC-HC. To find the bitrate for Xvid's maximum quality I ran a CQ2.0 encode (Home Theatre profile, one B-frame, VAQ enabled) then I used the resulting bitrate for 2 pass encodes (1050kbps). For x264 I used the default settings (no tuning etc). I assume those claiming Xvid is wonderful must at least be using the mpeg matrix.

These be thumbnails. Click for the full size version.
Source


x264


Xvid h263 matrix


Xvid mpeg matrix

Last edited by hello_hello; 14th April 2017 at 06:11.
hello_hello is offline   Reply With Quote
Old 14th April 2017, 08:27   #43  |  Link
Sharc
Registered User
 
Join Date: May 2006
Posts: 3,353
Quote:
Originally Posted by hello_hello View Post
....To find the bitrate for Xvid's maximum quality I ran a CQ2.0 encode (Home Theatre profile, one B-frame, VAQ enabled) then I used the resulting bitrate for 2 pass encodes (1050kbps).....
Interesting. This also means that higher bitrates for XviD would have no beneficial impact on the quality in this case.
It is also an explanation for some "undersizing" issues: The XviD encoder is saturated and doesn't waste extra bits for no benefit.
Sharc is offline   Reply With Quote
Old 14th April 2017, 09:03   #44  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Yeah the way I understand it, a long time ago the quantizers were changed so the minimum quantizers could be set to "1" to allow the encoder to spend extra bits when required, to help prevent undersized files, but as far as I know it does nothing to increase the quality. I don't know what it does with them, but I'm pretty sure CQ2.0 is maximum quality.
I remember back in the AutoGK days I'd occasionally specify too high a bitrate for one reason or another and end up with an undersized file, and AutoGK was very good at outputting the requested file size as a rule.

If you run a single pass, "100% quality" encode using AutoGK, you get a CQ2.0 encode, unless my memory is letting me down. 75% quality is CQ2.67, from memory.

Last edited by hello_hello; 14th April 2017 at 09:12.
hello_hello is offline   Reply With Quote
Old 14th April 2017, 09:53   #45  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Now I'm wondering if I was wrong when I said a minimum quantizer of "1" doesn't improve quality. I'm not sure if I'm interpreting the Xvid stats correctly, but for the first encode I specified a bitrate way higher than the encoder would be able to achieve.



For the second encode I specified a more sensible bitrate.



If nothing else, maybe forcing a minimum quantizer of "1" by specifying a really high bitrate will effectively improve the B-Frame quality, if the stats are anything to go by.

I probably should re-run my earlier test encodes at a much higher bitrate to see if the quality does improve.

Last edited by hello_hello; 14th April 2017 at 09:56.
hello_hello is offline   Reply With Quote
Old 14th April 2017, 10:28   #46  |  Link
Sharc
Registered User
 
Join Date: May 2006
Posts: 3,353
Yes, the quantizer range is 1 to 31, with 1 being generally considered very inefficient, means no to little quality improvement at "exploding" file size. Hence the more practical value of 2 for "maximum quality".
Two more parameters to play with for quality optimization for single-pass encodes are BRatio and BOffset which determine the value of the actual B-frame Quantizer from the quantizer values of the adjacent I or P frames. Oh yeah, long time ago ......

Edit:
I just found in my old notes that my recipe was for BRatio = 1.65 and BOffset = -0.25 (XViD defaults 1.5 and 1 respectively).
But don't quote me on that......

Last edited by Sharc; 14th April 2017 at 10:56.
Sharc is offline   Reply With Quote
Old 14th April 2017, 10:32   #47  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Looks like I'll have to do an about-face. I tried again using the h263 matrix while specifying a bitrate of 2050kbps. For some reason I actually got 2900kbps, maybe because it was a short sample, but the detail retention definitely improved. In fact I think this time the h263 matrix retained about the same amount of detail as the x264 encode, although at nearly 3x the bitrate you'd hope so.

Edit: For future reference I ran the encodes again with Xvid's overflow controls set to 10% and that way it hit the target bitrate of 2050kbps. It still wasn't doing quite as well as x264 in respect to fine detail retention even though it was now only twice the x264 bitrate, but it wasn't much worse over-all as the 2900kbps encodes when the overflow settings were 5% and it overshot the target bitrate of 2050kbps by quite a lot.

Xvid h263 matrix, 2900kbps


So I might have to eat my words about Xvid not being able to retain the same amount of detail as x264, assuming you let it use an extremely high bitrate (compared to x264), but even so, I'm not sure I'd be using a less efficient encoder unless I had a particular reason, such as hardware player compatibility.

Last edited by hello_hello; 19th April 2017 at 05:03.
hello_hello is offline   Reply With Quote
Old 14th April 2017, 22:45   #48  |  Link
johnmeyer
Registered User
 
Join Date: Feb 2002
Location: California
Posts: 2,038
Quote:
Originally Posted by Midzuki View Post
Answer me Herr Meyer, what made you conclude that I killfiled Mick because of a typo ...
Because of what you wrote. Here it is again:
Quote:
My nickname is Midzuki.
It was you who added the boldface on the letter "i" in order to indicate the correct spelling. Almost immediately after that statement you then said you are adding him to the ignore list. Thus, my conclusion was very straightforward.

I have no way of knowing your history with every member on this forum. All I know is what I read in that post.

Quote:
Originally Posted by Midzuki View Post
On the other hand, probably I'll killfile you @Videohelp.com
Wow, it is obvious that it doesn't take much to cross you. What the heck did I do over there? I think my history in both forums is one of helping people rather than engaging in this sort of nonsense.
johnmeyer is offline   Reply With Quote
Old 14th April 2017, 23:03   #49  |  Link
Midzuki
Unavailable
 
Join Date: Mar 2009
Location: offline
Posts: 1,477
<OFF-TOPIC>
Quote:
Originally Posted by johnmeyer View Post
Because of what you wrote. Here it is again:It was you who added the boldface on the letter "i" in order to indicate the correct spelling. Almost immediately after that statement you then said you are adding him to the ignore list. Thus, my conclusion was very straightforward.
Nope, your conclusion was trollish.
"Almost immediately" is what you say.
Why you wanted to ignore the paragraph below:
Quote:
If I complained about the installer, it's because its creators have been doing it all wrong.
I am not a newbie, sir.
I really don't (want to) know.

But again: ¿why the hell should I tolerate when someone miswrites my name?

BTW, I also don't like when people call me "Marisa" instead of «Marsia».

Over now.
</OFF-TOPIC>
Midzuki is offline   Reply With Quote
Old 15th April 2017, 00:45   #50  |  Link
davidhorman
I'm the Doctor
 
Join Date: Jan 2004
Posts: 1,505
Quote:
Originally Posted by Katie Boundary View Post
Quote:
Well, it depends on the picture resolution, doesn't it?
Let's go with 720x480
What? It wasn't a question - it does depend on the resolution.

Quote:
Originally Posted by Midzuko
But again: ¿why the hell should I tolerate when someone miswrites my name?
Because we're all just humans and we sometimes make mistakes and it doesn't indicate any intended insult and you're massively overreacting (to this and more besides, it seems).

That you blocked Mick because he misspelled your name was the only plausible conclusion I could come to, as well.
__________________
My AviSynth filters / I'm the Doctor
davidhorman is offline   Reply With Quote
Old 15th April 2017, 01:46   #51  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Quote:
Originally Posted by Sharc View Post
Edit:
I just found in my old notes that my recipe was for BRatio = 1.65 and BOffset = -0.25 (XViD defaults 1.5 and 1 respectively).
But don't quote me on that......
I haven't actually compared them for quality yet, but I ran a couple of quick encodes just to see what he effect would be. It certainly causes the encoder to spread the bits around differently, although in this case it also caused the encoder to miss the target bitrate (500kbps) by a bit more.

Defaults:


BRatio 1.65, BOffset -0.25

Last edited by hello_hello; 17th April 2017 at 16:02. Reason: spelling
hello_hello is offline   Reply With Quote
Old 15th April 2017, 01:52   #52  |  Link
Midzuki
Unavailable
 
Join Date: Mar 2009
Location: offline
Posts: 1,477
Quote:
Originally Posted by davidHORSE
That you blocked Mick because he misspelled your name was the only plausible conclusion I could come to, as well.
Congratulations, mr. davidHORSE.
Another troll for my ignore list.

Last edited by Midzuki; 15th April 2017 at 01:55. Reason: edit
Midzuki is offline   Reply With Quote
Old 15th April 2017, 02:51   #53  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Trolling is so 90's. The only trolls left are the ones who accuse others of trolling.
hello_hello is offline   Reply With Quote
Old 15th April 2017, 12:08   #54  |  Link
Midzuki
Unavailable
 
Join Date: Mar 2009
Location: offline
Posts: 1,477
Quote:
Originally Posted by hullo_hullo
Trolling is so 90's. The only trolls left are the ones who accuse others of trolling.
Such as yourself, hullo_hullo.

Yes, some low-IQ people decide to harass me because of something THEY THINK that happened, and then I have no right to complain, otherwise I am the one to be called "troll". Your logic is amazing. The logic of the emotional manipulators. The truth is, the only trolls left are the ones who claim to be "rational".
Midzuki is offline   Reply With Quote
Old 15th April 2017, 12:40   #55  |  Link
Sharc
Registered User
 
Join Date: May 2006
Posts: 3,353
Quote:
Originally Posted by hello_hello View Post
I haven't actually compared them for quality yet, but I ran a couple of quick encodes just to see what he effect would be. It certainly causes the encoder to spread the bits around differently, although in the case it also caused the encoder to miss the target bitrate (500kbps) by a bit more.

Defaults:


BRatio 1.65, BOffset -0.25
I am a bit surprised to see the big difference in quantization which you got for the 2 settings. Maybe it's source specific. Are you positive that you used the same matrix?
Sharc is offline   Reply With Quote
Old 15th April 2017, 17:37   #56  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Quote:
Originally Posted by Sharc View Post
I am a bit surprised to see the big difference in quantization which you got for the 2 settings. Maybe it's source specific. Are you positive that you used the same matrix?
Positive. I'm a bit short of time now, but I'll try again with a different source tomorrow and post the result.

Edit: Whoops, my bad. Thinking about it, I may have used BOffset = -2.5 instead of -0.25, being an idiot. I'll try again tomorrow.

Last edited by hello_hello; 15th April 2017 at 17:43.
hello_hello is offline   Reply With Quote
Old 16th April 2017, 11:45   #57  |  Link
hello_hello
Registered User
 
Join Date: Mar 2011
Posts: 3,681
Quote:
Originally Posted by Sharc View Post
I am a bit surprised to see the big difference in quantization which you got for the 2 settings. Maybe it's source specific. Are you positive that you used the same matrix?
Obviously I did have a stupid yesterday, here's the same test again with the same source.

I wouldn't even attempt to pick a quality winner at this stage as the source quality isn't all that high to begin with. I'll probably try again later with a much higher quality source. I can see frames are encoded differently, but at the moment they're mostly only a little different rather than better or worse as such.

Defaults:


BRatio 1.65, BOffset -0.25
hello_hello is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 20:47.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.